Engine RPM constant?

[wwarren]

I see in the specs for the 16KW model that the exercise mode runs at 2400 RPM and normal operaton is 3600 RPM which apparently accounts for the quieter exercise operation. Under normal operation, does the engine always run at 3600 RPM, or would it run slower/quieter as the load lessens? I'm imagining my home tonight, where basically the only loads are the occasional furnace fan and refrigerator and standby draws of TV's, etc. I'm probably not using more than 2kw at the moment.

[Kelly Myers]

Hi,
I am unaware of any variable speed natural gas fired generator. Depending on the number of poles in the stator, most generators will run at 1800RPM or 3600RPM. You can get into pole changing setups, (or variable speed) but these are not very common until 400kw in size. There are some smaller Variable speed constant frequency generators, but they do not fit the typical residential/small commercial setup.

Your 16kw gen-set will stay near 3600 rpms. This is what gives us 60hz on a two pole stator. It is the job of the governor to keep the engine at 3600 RPMS. If a large motor turns on, the generator will drop in speed until the locked rotor amperage is cleared. When a large motor turns off, the RPMS will jump over 3600. This is why an electronic governor yields cleaner power then a mechanical.

Fuel consumption will vary depending on how much resistance is on the engine itself. At idle(no load) your 16kw will consume 1 gallon of LP per hour. If you are using 33A per leg, you will be consuming around 1.6 gallons of LP per hour. If you are using 66A per leg, you will be consuming around 2.5 gallons per hour.